A TRIPHASIC ANALYSIS OF CORNEAL SWELLING AND HYDRATION CONTROL

Physiological studies strongly support the view that hydration control in the cornea is dependent on active ion transport ata the corneal en dothelium. However, the mechanism by which endothelial ion transport r egulates corneal thickness has not been elaborated in detail. In this study, the corneal stroma is modeled as a triphasic material under ste ady-state conditions. An ion flux boundary condition is developed to r epresent active transport at the endothelium. the equations are solved in cylindrical coordinates for confined compression and in spherical coordinates to represent an intact cornea. The model provides a mechan ism by which active ion transport at the endothelium regulates corneal hydration and provides a basis for explaining the origin of the ''imb ibition pressure'' and stromal ''swelling pressure.'' The model encaps ulates the Donnan view of corneal swelling as well as the ''pump-leak hypothesis.''.